wpmu_create_blog( string $domain, string $path, string $title, int $user_id, array $meta = array(), int $network_id = 1 )

function wpmu_create_blog( $domain, $path, $title, $user_id, $meta = array(), $network_id = 1 ) {
	$defaults = array(
		'public' => 0,
		'WPLANG' => get_network_option( $network_id, 'WPLANG' ),
	);
	$meta = wp_parse_args( $meta, $defaults );

	$domain = preg_replace( '/\s+/', '', sanitize_user( $domain, true ) );

	if ( is_subdomain_install() )
		$domain = str_replace( '@', '', $domain );

	$title = strip_tags( $title );
	$user_id = (int) $user_id;

	if ( empty($path) )
		$path = '/';

	// Check if the domain has been used already. We should return an error message.
	if ( domain_exists($domain, $path, $network_id) )
		return new WP_Error( 'blog_taken', __( 'Sorry, that site already exists!' ) );

	if ( ! wp_installing() ) {
		wp_installing( true );
	}

	if ( ! $blog_id = insert_blog($domain, $path, $network_id) )
		return new WP_Error('insert_blog', __('Could not create site.'));

	switch_to_blog($blog_id);
	install_blog($blog_id, $title);
	wp_install_defaults($user_id);

	add_user_to_blog($blog_id, $user_id, 'administrator');

	foreach ( $meta as $key => $value ) {
		if ( in_array( $key, array( 'public', 'archived', 'mature', 'spam', 'deleted', 'lang_id' ) ) )
			update_blog_status( $blog_id, $key, $value );
		else
			update_option( $key, $value );
	}

	update_option( 'blog_public', (int) $meta['public'] );

	if ( ! is_super_admin( $user_id ) && ! get_user_meta( $user_id, 'primary_blog', true ) )
		update_user_meta( $user_id, 'primary_blog', $blog_id );

	restore_current_blog();
	/**
	 * Fires immediately after a new site is created.
	 *
	 * @since WP-MU (3.0.0)
	 *
	 * @param int    $blog_id    Site ID.
	 * @param int    $user_id    User ID.
	 * @param string $domain     Site domain.
	 * @param string $path       Site path.
	 * @param int    $network_id Network ID. Only relevant on multi-network installations.
	 * @param array  $meta       Meta data. Used to set initial site options.
	 */
	do_action( 'wpmu_new_blog', $blog_id, $user_id, $domain, $path, $network_id, $meta );

	wp_cache_set( 'last_changed', microtime(), 'sites' );

	return $blog_id;
}